RAM or SSD Cache First?

[SdeGat]

I took advantage of Black Friday sales and just ordered a DS923+ that I will use for file storage and backup purposes.

For my use, my concern is maximizing transfer speeds and I just read that on Reddit:

« System RAM also caches I/O, so the SSD cache will only give you a boost if your frequently-used data set exceeds your RAM cache. You can see the memory cache size by going into Resource Monitor, select Memory, and it will show "Cached" as x GB down at the bottom.

Generally you should always max out system RAM prior to adding an SSD cache because a RAM cache is faster than SSD.

For SSDs, I don't recommend consumer models, stick with Synology or Seagate IronWolf 510. One advantage of Synology branded drives is that if you ever upgrade to DS923+ or later, the Synology drives will support an SSD volume where third-party drives will not. »

Is that accurate? Should I just get more RAM and forget about a cache SSD?

 

[EAZ1964]

If you want to maximize transferspeeds, the trick is to go beyond standard ethernet, either 10GE or double cables from NAS to devices (SMB multichannel).
Disk IO, like database acces can best be increased by using internal SSD in stead of HDD, as of the low access time of SSD. Some use a separate SSD pool for webserver or database.
RAM will help a lot in general, as less disk swap is needed, if you run Docker etc.
All depends on your use case.

 

[oRBIT]

SSD Cache reduces noise from the harddrives in your unit (if you're using mechanical drives), that's worth alot to me anyway.

 

[SdeGat]

Thanks @EAZ1964 and @oRBIT

I am still on standard Ethernet as my router and computer are a few years old. I’ll likely move to 2.5 or 10gbps as I upgrade those two. The 923+ will allow this.

I have mechanical HDDs and will likely have those for a while. Does that mean that SSD cache provides more overall benefit than RAM? I see that you have 32gb already @oRBIT.

 

[oRBIT]

They complement eachother I think.. If you're using the NAS only for storage and the basic stuff (=no Docker, VMM etc.) I don't think you need any additional RAM, the Cache-drives will possibly be a better investment in that scenario.

 

[oRBIT]

Congrats btw to your purchase. It's a very good device even if it lacks hardware-transcoding-capabilities for video.

 

[SdeGat]

Congrats btw to your purchase. It's a very good device even if it lacks hardware-transcoding-capabilities for video.

Thanks @oRBIT Since I don’t store/process any videos (except a few family things from iPhones), I should not miss that feature.

I’ll go back to my SSD research however. Do I need two SSDs for caching or just one works fine?

 

[Birdy]

Here you have all the information: Important considerations when creating SSD cache.

 

[SdeGat]

Here you have all the information: Important considerations when creating SSD cache.

Thanks @Birdy I had not read that specific item.

They don’t mention SHR though as this is what I intend to use with my different size HDDs.

 

[Birdy]

They don’t mention SHR though as this is what I intend to use with my different size HDDs.

That's correct, the KB is about SSD cache and you had not a question about SHR with your different size HDD's, thought.
Anyway, SHR is flexible with different sizes of HDDs.
What is Synology Hybrid RAID (SHR)?

 

[SdeGat]

That's correct, the KB is about SSD cache and you had not a question about SHR with your different size HDD's, thought.
Anyway, SHR is flexible with different sizes of HDDs.
What is Synology Hybrid RAID (SHR)?

So, if one is using SHR, the SSD cache info in the KB does not apply?